Digital Assessment at Peri-implant Tissues After Immediate Implants With Customized Healing Abutments and Connective Tissue Grafts

Volumetric Digital Analysis on the Effect of a Customized Healing Abutment With or Without Connective Tissue Graft at Maxillary Immediate Implant Sites - A Randomized Clinical Trial

After a single-tooth extraction, physiological remodeling processes are unavoidable which leads to a total loss of the periodontal ligament and resorption of the bundle bone. Immediate implant placement associated with bone substitutes and customized healing abutments seems to reduce the amount of resorption at peri-implant areas. Recently, studies evaluating the use of a connective tissue grafts are being conducted in order to assess possible final outcome advantages in immediate implant procedures. This study aims to evaluate peri-implant tissue dimensional changes after the use of a customized healing abutment with or without connective tissue graft in flapless maxillary immediate implant placement.

The present study was designed as a prospective, controlled clinical trial with a parallel-group design and balanced randomization (ratio 1:1) to document the peri-implant tissues response in using a customized healing abutment with a connective tissue graft (Test group) or without a connective tissue graft (Control group) xenogeneic collagen matrix (Group CM) or a customized healing abutment (Group CA) in flapless maxillary immediate implants. The protocol was reviewed and approved by the Institute of Bioethics of the Catholic University of Portugal (Project nº 139) and the patients included will be previously informed to participate in this investigation signing an informed consent considering the 1975 Declaration of Helsinki, revised in 2013. Group designation will be kept in opaque-sealed envelopes that will be opened after implant insertion by an investigator (D.F), not involved in surgical procedures, randomly allocating participants to one of the two treatment groups. Patients' inclusion criteria are: 1) ≥18 years of age; 2) patients who had a failing tooth and needed an implant placing therapy in the aesthetic zone (between 15-25); 3) the failing tooth has adjacent and opposing natural teeth; 4) sufficient mesial-distal and inter-occlusal space for placement of the implant and definitive restoration; 5) had an intact socket wall previously to the extraction; 6) had sufficient apical bone to place an immediate implant with minimum primary stability of 30 N/cm. Exclusion criteria are: individuals diagnosed with periodontal disease; medical and general contraindications for the surgical procedure; heavy smokers (> 10 cigarettes/day); an active infection at the implant site. A CONSORT 2010 check-list will be also performed in order to consider an appropriate guideline for the present randomized trial study.

All surgical procedures will be conducted under appropriate local anesthesia 4% articaine with adrenaline 1:100000 (UbistesinTM, 3M-ESPE, St. Paul, MN, USA). In both groups, flapless tooth extractions will be performed after sectioning the tooth, followed by the use of periotomes and elevators to separate the two parts of the tooth, avoiding damage to the buccal and palatal bone plates. All patients will be treated with cylindrical shape implants (OsseoSpeed EV™, AstraTech Implant System, Dentsply Implants, Möhndal, Sweden) with a narrow diameter internal connection platform following the surgical sequence protocol provided by the manufacturer. Both groups will receive a customized healing abutment made of polymethyl methacrylate (PMMA) material, designed and fabricated accordingly with the gingival contour of the original tooth. Patients included in the Test group will receive connective tissue grafts harvested using the single incision technique.

A protocol was elaborated to study the variables of interest. One examiner, blinded for the surgical procedure, will be calibrated through an intra-examiner test (Dahlberg d-value), consisting in a double consecutive data collection of 10 randomly chosen patients included in this study.

Data collection will be performed in four appointments. A Cone Beam Computer Tomography (CBCT) evaluation (Ortophos XG 3D®, Sirona Dental Systems GmbH, Bensheim, Germany) will be performed before tooth extraction and implant placement (T0). At this point, two clinical parameters will be assessed with a periodontal probe (PCB 12; Hu-Friedy, Chicago, IL, USA) to the nearest millimeter: BID (distance between implant shoulder and the buccal bone plate) and KM (distance between the gingival groove and the mucogingival junction). Digital impressions (Cerec Omnicam®, Sirona Dental Systems GmbH, Bensheim, Germany) will be taken prior to extraction (T0), one month (T1), four months (T2) and 12 months (T3) after implant insertion allowing to superimpose the digital files and to evaluate volumetric changes between different time points at peri-implant tissue areas like Buccal Volume Variation (BVv) and Total Volume Variation (TVv). Mucosa variation between T0 and T3 will be digitally computed assessing the papilla presence at mesial (MPHv) and distal (DPHv) sites and the mucosa height (MGHv). Mean values will be compared and statistical significance will be at 0,05.

Inclusion Criteria:

• 1) ≥18 years of age; 2) patients who had a failing tooth and needed an implant placing therapy in the aesthetic zone (between 15-25); 3) the failing tooth has adjacent and opposing natural teeth; 4) sufficient mesial-distal and inter-occlusal space for placement of the implant and definitive restoration; 5) had an intact socket wall previously to the extraction; 6) had sufficient apical bone to place an immediate implant with minimum primary stability of 30 N/cm.

Exclusion Criteria:

• individuals diagnosed with periodontal disease; medical and general contraindications for the surgical procedure; heavy smokers (> 10 cigarettes/day); an active infection at the implant site.